Numerous different gas metal arc welding (GMAW) processes have been widely utilized throughout the United States and elsewhere with metals such as cold rolled steel, stainless steel, and aluminum, nickel, copper, titanium, cobalt and their alloys. Such processes generally utilize an inert or partially-reactive gas of uniform composition for protecting or shielding the molten welding filler material and its adjacent workpiece welding site primarily from the effects of environmental oxygen and environmental nitrogen, and are satisfactory for many known welding applications. However, the known gas metal arc welding (GMAW) processes are often found to be unsatisfactory for welding particular metals. These include certain aerospace industry-utilized nickel-based super alloys, which are normally difficult-to-weld and sometimes also susceptible to metal composition degradation or micro-cracking at and near the weld bond line. The gas metal arc welding processes also have been found to be unsatisfactory for welding relatively thin metal sheet materials, for welding small, highly precise metal assemblies, and for welding at difficult-to-access metal workpiece locations.
We have discovered that many of the fabrication and metallurgical shortcomings associated with the prior art GMAW processes may be overcome by using the method steps and apparatus of the present invention. Also, other advantages of the present invention will become apparent from study of the drawings, detailed descriptions, and claims which follow.